Dual fuel engines are known for various applications, such as generator sets, engine-driven compressors, engine driven pumps, machine, off-highway trucks and others. Typically, such engines are stationary and operate in the field. The operation of such engines by substitution of a certain amount of heavy fuel, such as diesel, with a lighter fuel, such as natural gas, biogas, liquid petroleum gas (LPG) or other types of fuel that may be more readily available and cost effective, makes them more effective to operate.
Nevertheless, to achieve desired emission levels, dual fuel engines require emission control systems such as exhaust gas recirculation (EGR) to reduce nitrous oxide (NOx) emissions. EGR systems, like other emission control systems, are generally complex and expensive but required to meet emission levels.